crypto/openssh/ssh-agent.c

   1 /* $OpenBSD: ssh-agent.c,v 1.153 2006/10/06 02:29:19 djm Exp $ */
   2 /*
   3  * Author: Tatu Ylonen <ylo@cs.hut.fi>
   4  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
   5  *                    All rights reserved
   6  * The authentication agent program.
   7  *
   8  * As far as I am concerned, the code I have written for this software
   9  * can be used freely for any purpose.  Any derived versions of this
  10  * software must be clearly marked as such, and if the derived work is
  11  * incompatible with the protocol description in the RFC file, it must be
  12  * called by a name other than "ssh" or "Secure Shell".
  13  *
  14  * Copyright (c) 2000, 2001 Markus Friedl.  All rights reserved.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  *
  25  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  26  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  27  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  28  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  29  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  30  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  31  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  32  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  33  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  34  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  35  */
  36
  37 #include "includes.h"
  38 __RCSID("$FreeBSD$");
  39
  40 #include <sys/types.h>
  41 #include <sys/param.h>
  42 #include <sys/resource.h>
  43 #include <sys/stat.h>
  44 #include <sys/socket.h>
  45 #ifdef HAVE_SYS_TIME_H
  46 # include <sys/time.h>
  47 #endif
  48 #ifdef HAVE_SYS_UN_H
  49 # include <sys/un.h>
  50 #endif
  51 #include "openbsd-compat/sys-queue.h"
  52
  53 #include <openssl/evp.h>
  54 #include <openssl/md5.h>
  55
  56 #include <errno.h>
  57 #include <fcntl.h>
  58 #ifdef HAVE_PATHS_H
  59 # include <paths.h>
  60 #endif
  61 #include <signal.h>
  62 #include <stdarg.h>
  63 #include <stdio.h>
  64 #include <stdlib.h>
  65 #include <time.h>
  66 #include <string.h>
  67 #include <unistd.h>
  68
  69 #include "xmalloc.h"
  70 #include "ssh.h"
  71 #include "rsa.h"
  72 #include "buffer.h"
  73 #include "key.h"
  74 #include "authfd.h"
  75 #include "compat.h"
  76 #include "log.h"
  77 #include "misc.h"
  78
  79 #ifdef SMARTCARD
  80 #include "scard.h"
  81 #endif
  82
  83 #if defined(HAVE_SYS_PRCTL_H)
  84 #include <sys/prctl.h>  /* For prctl() and PR_SET_DUMPABLE */
  85 #endif
  86
  87 typedef enum {
  88         AUTH_UNUSED,
  89         AUTH_SOCKET,
  90         AUTH_CONNECTION
  91 } sock_type;
  92
  93 typedef struct {
  94         int fd;
  95         sock_type type;
  96         Buffer input;
  97         Buffer output;
  98         Buffer request;
  99 } SocketEntry;
 100
 101 u_int sockets_alloc = 0;
 102 SocketEntry *sockets = NULL;
 103
 104 typedef struct identity {
 105         TAILQ_ENTRY(identity) next;
 106         Key *key;
 107         char *comment;
 108         u_int death;
 109         u_int confirm;
 110 } Identity;
 111
 112 typedef struct {
 113         int nentries;
 114         TAILQ_HEAD(idqueue, identity) idlist;
 115 } Idtab;
 116
 117 /* private key table, one per protocol version */
 118 Idtab idtable[3];
 119
 120 int max_fd = 0;
 121
 122 /* pid of shell == parent of agent */
 123 pid_t parent_pid = -1;
 124
 125 /* pathname and directory for AUTH_SOCKET */
 126 char socket_name[MAXPATHLEN];
 127 char socket_dir[MAXPATHLEN];
 128
 129 /* locking */
 130 int locked = 0;
 131 char *lock_passwd = NULL;
 132
 133 extern char *__progname;
 134
 135 /* Default lifetime (0 == forever) */
 136 static int lifetime = 0;
 137
 138 static void
 139 close_socket(SocketEntry *e)
 140 {
 141         close(e->fd);
 142         e->fd = -1;
 143         e->type = AUTH_UNUSED;
 144         buffer_free(&e->input);
 145         buffer_free(&e->output);
 146         buffer_free(&e->request);
 147 }
 148
 149 static void
 150 idtab_init(void)
 151 {
 152         int i;
 153
 154         for (i = 0; i <=2; i++) {
 155                 TAILQ_INIT(&idtable[i].idlist);
 156                 idtable[i].nentries = 0;
 157         }
 158 }
 159
 160 /* return private key table for requested protocol version */
 161 static Idtab *
 162 idtab_lookup(int version)
 163 {
 164         if (version < 1 || version > 2)
 165                 fatal("internal error, bad protocol version %d", version);
 166         return &idtable[version];
 167 }
 168
 169 static void
 170 free_identity(Identity *id)
 171 {
 172         key_free(id->key);
 173         xfree(id->comment);
 174         xfree(id);
 175 }
 176
 177 /* return matching private key for given public key */
 178 static Identity *
 179 lookup_identity(Key *key, int version)
 180 {
 181         Identity *id;
 182
 183         Idtab *tab = idtab_lookup(version);
 184         TAILQ_FOREACH(id, &tab->idlist, next) {
 185                 if (key_equal(key, id->key))
 186                         return (id);
 187         }
 188         return (NULL);
 189 }
 190
 191 /* Check confirmation of keysign request */
 192 static int
 193 confirm_key(Identity *id)
 194 {
 195         char *p;
 196         int ret = -1;
 197
 198         p = key_fingerprint(id->key, SSH_FP_MD5, SSH_FP_HEX);
 199         if (ask_permission("Allow use of key %s?\nKey fingerprint %s.",
 200             id->comment, p))
 201                 ret = 0;
 202         xfree(p);
 203
 204         return (ret);
 205 }
 206
 207 /* send list of supported public keys to 'client' */
 208 static void
 209 process_request_identities(SocketEntry *e, int version)
 210 {
 211         Idtab *tab = idtab_lookup(version);
 212         Identity *id;
 213         Buffer msg;
 214
 215         buffer_init(&msg);
 216         buffer_put_char(&msg, (version == 1) ?
 217             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 218         buffer_put_int(&msg, tab->nentries);
 219         TAILQ_FOREACH(id, &tab->idlist, next) {
 220                 if (id->key->type == KEY_RSA1) {
 221                         buffer_put_int(&msg, BN_num_bits(id->key->rsa->n));
 222                         buffer_put_bignum(&msg, id->key->rsa->e);
 223                         buffer_put_bignum(&msg, id->key->rsa->n);
 224                 } else {
 225                         u_char *blob;
 226                         u_int blen;
 227                         key_to_blob(id->key, &blob, &blen);
 228                         buffer_put_string(&msg, blob, blen);
 229                         xfree(blob);
 230                 }
 231                 buffer_put_cstring(&msg, id->comment);
 232         }
 233         buffer_put_int(&e->output, buffer_len(&msg));
 234         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 235         buffer_free(&msg);
 236 }
 237
 238 /* ssh1 only */
 239 static void
 240 process_authentication_challenge1(SocketEntry *e)
 241 {
 242         u_char buf[32], mdbuf[16], session_id[16];
 243         u_int response_type;
 244         BIGNUM *challenge;
 245         Identity *id;
 246         int i, len;
 247         Buffer msg;
 248         MD5_CTX md;
 249         Key *key;
 250
 251         buffer_init(&msg);
 252         key = key_new(KEY_RSA1);
 253         if ((challenge = BN_new()) == NULL)
 254                 fatal("process_authentication_challenge1: BN_new failed");
 255
 256         (void) buffer_get_int(&e->request);                     /* ignored */
 257         buffer_get_bignum(&e->request, key->rsa->e);
 258         buffer_get_bignum(&e->request, key->rsa->n);
 259         buffer_get_bignum(&e->request, challenge);
 260
 261         /* Only protocol 1.1 is supported */
 262         if (buffer_len(&e->request) == 0)
 263                 goto failure;
 264         buffer_get(&e->request, session_id, 16);
 265         response_type = buffer_get_int(&e->request);
 266         if (response_type != 1)
 267                 goto failure;
 268
 269         id = lookup_identity(key, 1);
 270         if (id != NULL && (!id->confirm || confirm_key(id) == 0)) {
 271                 Key *private = id->key;
 272                 /* Decrypt the challenge using the private key. */
 273                 if (rsa_private_decrypt(challenge, challenge, private->rsa) <= 0)
 274                         goto failure;
 275
 276                 /* The response is MD5 of decrypted challenge plus session id. */
 277                 len = BN_num_bytes(challenge);
 278                 if (len <= 0 || len > 32) {
 279                         logit("process_authentication_challenge: bad challenge length %d", len);
 280                         goto failure;
 281                 }
 282                 memset(buf, 0, 32);
 283                 BN_bn2bin(challenge, buf + 32 - len);
 284                 MD5_Init(&md);
 285                 MD5_Update(&md, buf, 32);
 286                 MD5_Update(&md, session_id, 16);
 287                 MD5_Final(mdbuf, &md);
 288
 289                 /* Send the response. */
 290                 buffer_put_char(&msg, SSH_AGENT_RSA_RESPONSE);
 291                 for (i = 0; i < 16; i++)
 292                         buffer_put_char(&msg, mdbuf[i]);
 293                 goto send;
 294         }
 295
 296 failure:
 297         /* Unknown identity or protocol error.  Send failure. */
 298         buffer_put_char(&msg, SSH_AGENT_FAILURE);
 299 send:
 300         buffer_put_int(&e->output, buffer_len(&msg));
 301         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 302         key_free(key);
 303         BN_clear_free(challenge);
 304         buffer_free(&msg);
 305 }
 306
 307 /* ssh2 only */
 308 static void
 309 process_sign_request2(SocketEntry *e)
 310 {
 311         u_char *blob, *data, *signature = NULL;
 312         u_int blen, dlen, slen = 0;
 313         extern int datafellows;
 314         int ok = -1, flags;
 315         Buffer msg;
 316         Key *key;
 317
 318         datafellows = 0;
 319
 320         blob = buffer_get_string(&e->request, &blen);
 321         data = buffer_get_string(&e->request, &dlen);
 322
 323         flags = buffer_get_int(&e->request);
 324         if (flags & SSH_AGENT_OLD_SIGNATURE)
 325                 datafellows = SSH_BUG_SIGBLOB;
 326
 327         key = key_from_blob(blob, blen);
 328         if (key != NULL) {
 329                 Identity *id = lookup_identity(key, 2);
 330                 if (id != NULL && (!id->confirm || confirm_key(id) == 0))
 331                         ok = key_sign(id->key, &signature, &slen, data, dlen);
 332                 key_free(key);
 333         }
 334         buffer_init(&msg);
 335         if (ok == 0) {
 336                 buffer_put_char(&msg, SSH2_AGENT_SIGN_RESPONSE);
 337                 buffer_put_string(&msg, signature, slen);
 338         } else {
 339                 buffer_put_char(&msg, SSH_AGENT_FAILURE);
 340         }
 341         buffer_put_int(&e->output, buffer_len(&msg));
 342         buffer_append(&e->output, buffer_ptr(&msg),
 343             buffer_len(&msg));
 344         buffer_free(&msg);
 345         xfree(data);
 346         xfree(blob);
 347         if (signature != NULL)
 348                 xfree(signature);
 349 }
 350
 351 /* shared */
 352 static void
 353 process_remove_identity(SocketEntry *e, int version)
 354 {
 355         u_int blen, bits;
 356         int success = 0;
 357         Key *key = NULL;
 358         u_char *blob;
 359
 360         switch (version) {
 361         case 1:
 362                 key = key_new(KEY_RSA1);
 363                 bits = buffer_get_int(&e->request);
 364                 buffer_get_bignum(&e->request, key->rsa->e);
 365                 buffer_get_bignum(&e->request, key->rsa->n);
 366
 367                 if (bits != key_size(key))
 368                         logit("Warning: identity keysize mismatch: actual %u, announced %u",
 369                             key_size(key), bits);
 370                 break;
 371         case 2:
 372                 blob = buffer_get_string(&e->request, &blen);
 373                 key = key_from_blob(blob, blen);
 374                 xfree(blob);
 375                 break;
 376         }
 377         if (key != NULL) {
 378                 Identity *id = lookup_identity(key, version);
 379                 if (id != NULL) {
 380                         /*
 381                          * We have this key.  Free the old key.  Since we
 382                          * don't want to leave empty slots in the middle of
 383                          * the array, we actually free the key there and move
 384                          * all the entries between the empty slot and the end
 385                          * of the array.
 386                          */
 387                         Idtab *tab = idtab_lookup(version);
 388                         if (tab->nentries < 1)
 389                                 fatal("process_remove_identity: "
 390                                     "internal error: tab->nentries %d",
 391                                     tab->nentries);
 392                         TAILQ_REMOVE(&tab->idlist, id, next);
 393                         free_identity(id);
 394                         tab->nentries--;
 395                         success = 1;
 396                 }
 397                 key_free(key);
 398         }
 399         buffer_put_int(&e->output, 1);
 400         buffer_put_char(&e->output,
 401             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 402 }
 403
 404 static void
 405 process_remove_all_identities(SocketEntry *e, int version)
 406 {
 407         Idtab *tab = idtab_lookup(version);
 408         Identity *id;
 409
 410         /* Loop over all identities and clear the keys. */
 411         for (id = TAILQ_FIRST(&tab->idlist); id;
 412             id = TAILQ_FIRST(&tab->idlist)) {
 413                 TAILQ_REMOVE(&tab->idlist, id, next);
 414                 free_identity(id);
 415         }
 416
 417         /* Mark that there are no identities. */
 418         tab->nentries = 0;
 419
 420         /* Send success. */
 421         buffer_put_int(&e->output, 1);
 422         buffer_put_char(&e->output, SSH_AGENT_SUCCESS);
 423 }
 424
 425 static void
 426 reaper(void)
 427 {
 428         u_int now = time(NULL);
 429         Identity *id, *nxt;
 430         int version;
 431         Idtab *tab;
 432
 433         for (version = 1; version < 3; version++) {
 434                 tab = idtab_lookup(version);
 435                 for (id = TAILQ_FIRST(&tab->idlist); id; id = nxt) {
 436                         nxt = TAILQ_NEXT(id, next);
 437                         if (id->death != 0 && now >= id->death) {
 438                                 TAILQ_REMOVE(&tab->idlist, id, next);
 439                                 free_identity(id);
 440                                 tab->nentries--;
 441                         }
 442                 }
 443         }
 444 }
 445
 446 static void
 447 process_add_identity(SocketEntry *e, int version)
 448 {
 449         Idtab *tab = idtab_lookup(version);
 450         int type, success = 0, death = 0, confirm = 0;
 451         char *type_name, *comment;
 452         Key *k = NULL;
 453
 454         switch (version) {
 455         case 1:
 456                 k = key_new_private(KEY_RSA1);
 457                 (void) buffer_get_int(&e->request);             /* ignored */
 458                 buffer_get_bignum(&e->request, k->rsa->n);
 459                 buffer_get_bignum(&e->request, k->rsa->e);
 460                 buffer_get_bignum(&e->request, k->rsa->d);
 461                 buffer_get_bignum(&e->request, k->rsa->iqmp);
 462
 463                 /* SSH and SSL have p and q swapped */
 464                 buffer_get_bignum(&e->request, k->rsa->q);      /* p */
 465                 buffer_get_bignum(&e->request, k->rsa->p);      /* q */
 466
 467                 /* Generate additional parameters */
 468                 rsa_generate_additional_parameters(k->rsa);
 469                 break;
 470         case 2:
 471                 type_name = buffer_get_string(&e->request, NULL);
 472                 type = key_type_from_name(type_name);
 473                 xfree(type_name);
 474                 switch (type) {
 475                 case KEY_DSA:
 476                         k = key_new_private(type);
 477                         buffer_get_bignum2(&e->request, k->dsa->p);
 478                         buffer_get_bignum2(&e->request, k->dsa->q);
 479                         buffer_get_bignum2(&e->request, k->dsa->g);
 480                         buffer_get_bignum2(&e->request, k->dsa->pub_key);
 481                         buffer_get_bignum2(&e->request, k->dsa->priv_key);
 482                         break;
 483                 case KEY_RSA:
 484                         k = key_new_private(type);
 485                         buffer_get_bignum2(&e->request, k->rsa->n);
 486                         buffer_get_bignum2(&e->request, k->rsa->e);
 487                         buffer_get_bignum2(&e->request, k->rsa->d);
 488                         buffer_get_bignum2(&e->request, k->rsa->iqmp);
 489                         buffer_get_bignum2(&e->request, k->rsa->p);
 490                         buffer_get_bignum2(&e->request, k->rsa->q);
 491
 492                         /* Generate additional parameters */
 493                         rsa_generate_additional_parameters(k->rsa);
 494                         break;
 495                 default:
 496                         buffer_clear(&e->request);
 497                         goto send;
 498                 }
 499                 break;
 500         }
 501         /* enable blinding */
 502         switch (k->type) {
 503         case KEY_RSA:
 504         case KEY_RSA1:
 505                 if (RSA_blinding_on(k->rsa, NULL) != 1) {
 506                         error("process_add_identity: RSA_blinding_on failed");
 507                         key_free(k);
 508                         goto send;
 509                 }
 510                 break;
 511         }
 512         comment = buffer_get_string(&e->request, NULL);
 513         if (k == NULL) {
 514                 xfree(comment);
 515                 goto send;
 516         }
 517         success = 1;
 518         while (buffer_len(&e->request)) {
 519                 switch (buffer_get_char(&e->request)) {
 520                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 521                         death = time(NULL) + buffer_get_int(&e->request);
 522                         break;
 523                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 524                         confirm = 1;
 525                         break;
 526                 default:
 527                         break;
 528                 }
 529         }
 530         if (lifetime && !death)
 531                 death = time(NULL) + lifetime;
 532         if (lookup_identity(k, version) == NULL) {
 533                 Identity *id = xmalloc(sizeof(Identity));
 534                 id->key = k;
 535                 id->comment = comment;
 536                 id->death = death;
 537                 id->confirm = confirm;
 538                 TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 539                 /* Increment the number of identities. */
 540                 tab->nentries++;
 541         } else {
 542                 key_free(k);
 543                 xfree(comment);
 544         }
 545 send:
 546         buffer_put_int(&e->output, 1);
 547         buffer_put_char(&e->output,
 548             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 549 }
 550
 551 /* XXX todo: encrypt sensitive data with passphrase */
 552 static void
 553 process_lock_agent(SocketEntry *e, int lock)
 554 {
 555         int success = 0;
 556         char *passwd;
 557
 558         passwd = buffer_get_string(&e->request, NULL);
 559         if (locked && !lock && strcmp(passwd, lock_passwd) == 0) {
 560                 locked = 0;
 561                 memset(lock_passwd, 0, strlen(lock_passwd));
 562                 xfree(lock_passwd);
 563                 lock_passwd = NULL;
 564                 success = 1;
 565         } else if (!locked && lock) {
 566                 locked = 1;
 567                 lock_passwd = xstrdup(passwd);
 568                 success = 1;
 569         }
 570         memset(passwd, 0, strlen(passwd));
 571         xfree(passwd);
 572
 573         buffer_put_int(&e->output, 1);
 574         buffer_put_char(&e->output,
 575             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 576 }
 577
 578 static void
 579 no_identities(SocketEntry *e, u_int type)
 580 {
 581         Buffer msg;
 582
 583         buffer_init(&msg);
 584         buffer_put_char(&msg,
 585             (type == SSH_AGENTC_REQUEST_RSA_IDENTITIES) ?
 586             SSH_AGENT_RSA_IDENTITIES_ANSWER : SSH2_AGENT_IDENTITIES_ANSWER);
 587         buffer_put_int(&msg, 0);
 588         buffer_put_int(&e->output, buffer_len(&msg));
 589         buffer_append(&e->output, buffer_ptr(&msg), buffer_len(&msg));
 590         buffer_free(&msg);
 591 }
 592
 593 #ifdef SMARTCARD
 594 static void
 595 process_add_smartcard_key (SocketEntry *e)
 596 {
 597         char *sc_reader_id = NULL, *pin;
 598         int i, version, success = 0, death = 0, confirm = 0;
 599         Key **keys, *k;
 600         Identity *id;
 601         Idtab *tab;
 602
 603         sc_reader_id = buffer_get_string(&e->request, NULL);
 604         pin = buffer_get_string(&e->request, NULL);
 605
 606         while (buffer_len(&e->request)) {
 607                 switch (buffer_get_char(&e->request)) {
 608                 case SSH_AGENT_CONSTRAIN_LIFETIME:
 609                         death = time(NULL) + buffer_get_int(&e->request);
 610                         break;
 611                 case SSH_AGENT_CONSTRAIN_CONFIRM:
 612                         confirm = 1;
 613                         break;
 614                 default:
 615                         break;
 616                 }
 617         }
 618         if (lifetime && !death)
 619                 death = time(NULL) + lifetime;
 620
 621         keys = sc_get_keys(sc_reader_id, pin);
 622         xfree(sc_reader_id);
 623         xfree(pin);
 624
 625         if (keys == NULL || keys[0] == NULL) {
 626                 error("sc_get_keys failed");
 627                 goto send;
 628         }
 629         for (i = 0; keys[i] != NULL; i++) {
 630                 k = keys[i];
 631                 version = k->type == KEY_RSA1 ? 1 : 2;
 632                 tab = idtab_lookup(version);
 633                 if (lookup_identity(k, version) == NULL) {
 634                         id = xmalloc(sizeof(Identity));
 635                         id->key = k;
 636                         id->comment = sc_get_key_label(k);
 637                         id->death = death;
 638                         id->confirm = confirm;
 639                         TAILQ_INSERT_TAIL(&tab->idlist, id, next);
 640                         tab->nentries++;
 641                         success = 1;
 642                 } else {
 643                         key_free(k);
 644                 }
 645                 keys[i] = NULL;
 646         }
 647         xfree(keys);
 648 send:
 649         buffer_put_int(&e->output, 1);
 650         buffer_put_char(&e->output,
 651             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 652 }
 653
 654 static void
 655 process_remove_smartcard_key(SocketEntry *e)
 656 {
 657         char *sc_reader_id = NULL, *pin;
 658         int i, version, success = 0;
 659         Key **keys, *k = NULL;
 660         Identity *id;
 661         Idtab *tab;
 662
 663         sc_reader_id = buffer_get_string(&e->request, NULL);
 664         pin = buffer_get_string(&e->request, NULL);
 665         keys = sc_get_keys(sc_reader_id, pin);
 666         xfree(sc_reader_id);
 667         xfree(pin);
 668
 669         if (keys == NULL || keys[0] == NULL) {
 670                 error("sc_get_keys failed");
 671                 goto send;
 672         }
 673         for (i = 0; keys[i] != NULL; i++) {
 674                 k = keys[i];
 675                 version = k->type == KEY_RSA1 ? 1 : 2;
 676                 if ((id = lookup_identity(k, version)) != NULL) {
 677                         tab = idtab_lookup(version);
 678                         TAILQ_REMOVE(&tab->idlist, id, next);
 679                         tab->nentries--;
 680                         free_identity(id);
 681                         success = 1;
 682                 }
 683                 key_free(k);
 684                 keys[i] = NULL;
 685         }
 686         xfree(keys);
 687 send:
 688         buffer_put_int(&e->output, 1);
 689         buffer_put_char(&e->output,
 690             success ? SSH_AGENT_SUCCESS : SSH_AGENT_FAILURE);
 691 }
 692 #endif /* SMARTCARD */
 693
 694 /* dispatch incoming messages */
 695
 696 static void
 697 process_message(SocketEntry *e)
 698 {
 699         u_int msg_len, type;
 700         u_char *cp;
 701
 702         /* kill dead keys */
 703         reaper();
 704
 705         if (buffer_len(&e->input) < 5)
 706                 return;         /* Incomplete message. */
 707         cp = buffer_ptr(&e->input);
 708         msg_len = get_u32(cp);
 709         if (msg_len > 256 * 1024) {
 710                 close_socket(e);
 711                 return;
 712         }
 713         if (buffer_len(&e->input) < msg_len + 4)
 714                 return;
 715
 716         /* move the current input to e->request */
 717         buffer_consume(&e->input, 4);
 718         buffer_clear(&e->request);
 719         buffer_append(&e->request, buffer_ptr(&e->input), msg_len);
 720         buffer_consume(&e->input, msg_len);
 721         type = buffer_get_char(&e->request);
 722
 723         /* check wheter agent is locked */
 724         if (locked && type != SSH_AGENTC_UNLOCK) {
 725                 buffer_clear(&e->request);
 726                 switch (type) {
 727                 case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 728                 case SSH2_AGENTC_REQUEST_IDENTITIES:
 729                         /* send empty lists */
 730                         no_identities(e, type);
 731                         break;
 732                 default:
 733                         /* send a fail message for all other request types */
 734                         buffer_put_int(&e->output, 1);
 735                         buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 736                 }
 737                 return;
 738         }
 739
 740         debug("type %d", type);
 741         switch (type) {
 742         case SSH_AGENTC_LOCK:
 743         case SSH_AGENTC_UNLOCK:
 744                 process_lock_agent(e, type == SSH_AGENTC_LOCK);
 745                 break;
 746         /* ssh1 */
 747         case SSH_AGENTC_RSA_CHALLENGE:
 748                 process_authentication_challenge1(e);
 749                 break;
 750         case SSH_AGENTC_REQUEST_RSA_IDENTITIES:
 751                 process_request_identities(e, 1);
 752                 break;
 753         case SSH_AGENTC_ADD_RSA_IDENTITY:
 754         case SSH_AGENTC_ADD_RSA_ID_CONSTRAINED:
 755                 process_add_identity(e, 1);
 756                 break;
 757         case SSH_AGENTC_REMOVE_RSA_IDENTITY:
 758                 process_remove_identity(e, 1);
 759                 break;
 760         case SSH_AGENTC_REMOVE_ALL_RSA_IDENTITIES:
 761                 process_remove_all_identities(e, 1);
 762                 break;
 763         /* ssh2 */
 764         case SSH2_AGENTC_SIGN_REQUEST:
 765                 process_sign_request2(e);
 766                 break;
 767         case SSH2_AGENTC_REQUEST_IDENTITIES:
 768                 process_request_identities(e, 2);
 769                 break;
 770         case SSH2_AGENTC_ADD_IDENTITY:
 771         case SSH2_AGENTC_ADD_ID_CONSTRAINED:
 772                 process_add_identity(e, 2);
 773                 break;
 774         case SSH2_AGENTC_REMOVE_IDENTITY:
 775                 process_remove_identity(e, 2);
 776                 break;
 777         case SSH2_AGENTC_REMOVE_ALL_IDENTITIES:
 778                 process_remove_all_identities(e, 2);
 779                 break;
 780 #ifdef SMARTCARD
 781         case SSH_AGENTC_ADD_SMARTCARD_KEY:
 782         case SSH_AGENTC_ADD_SMARTCARD_KEY_CONSTRAINED:
 783                 process_add_smartcard_key(e);
 784                 break;
 785         case SSH_AGENTC_REMOVE_SMARTCARD_KEY:
 786                 process_remove_smartcard_key(e);
 787                 break;
 788 #endif /* SMARTCARD */
 789         default:
 790                 /* Unknown message.  Respond with failure. */
 791                 error("Unknown message %d", type);
 792                 buffer_clear(&e->request);
 793                 buffer_put_int(&e->output, 1);
 794                 buffer_put_char(&e->output, SSH_AGENT_FAILURE);
 795                 break;
 796         }
 797 }
 798
 799 static void
 800 new_socket(sock_type type, int fd)
 801 {
 802         u_int i, old_alloc, new_alloc;
 803
 804         set_nonblock(fd);
 805
 806         if (fd > max_fd)
 807                 max_fd = fd;
 808
 809         for (i = 0; i < sockets_alloc; i++)
 810                 if (sockets[i].type == AUTH_UNUSED) {
 811                         sockets[i].fd = fd;
 812                         buffer_init(&sockets[i].input);
 813                         buffer_init(&sockets[i].output);
 814                         buffer_init(&sockets[i].request);
 815                         sockets[i].type = type;
 816                         return;
 817                 }
 818         old_alloc = sockets_alloc;
 819         new_alloc = sockets_alloc + 10;
 820         sockets = xrealloc(sockets, new_alloc, sizeof(sockets[0]));
 821         for (i = old_alloc; i < new_alloc; i++)
 822                 sockets[i].type = AUTH_UNUSED;
 823         sockets_alloc = new_alloc;
 824         sockets[old_alloc].fd = fd;
 825         buffer_init(&sockets[old_alloc].input);
 826         buffer_init(&sockets[old_alloc].output);
 827         buffer_init(&sockets[old_alloc].request);
 828         sockets[old_alloc].type = type;
 829 }
 830
 831 static int
 832 prepare_select(fd_set **fdrp, fd_set **fdwp, int *fdl, u_int *nallocp)
 833 {
 834         u_int i, sz;
 835         int n = 0;
 836
 837         for (i = 0; i < sockets_alloc; i++) {
 838                 switch (sockets[i].type) {
 839                 case AUTH_SOCKET:
 840                 case AUTH_CONNECTION:
 841                         n = MAX(n, sockets[i].fd);
 842                         break;
 843                 case AUTH_UNUSED:
 844                         break;
 845                 default:
 846                         fatal("Unknown socket type %d", sockets[i].type);
 847                         break;
 848                 }
 849         }
 850
 851         sz = howmany(n+1, NFDBITS) * sizeof(fd_mask);
 852         if (*fdrp == NULL || sz > *nallocp) {
 853                 if (*fdrp)
 854                         xfree(*fdrp);
 855                 if (*fdwp)
 856                         xfree(*fdwp);
 857                 *fdrp = xmalloc(sz);
 858                 *fdwp = xmalloc(sz);
 859                 *nallocp = sz;
 860         }
 861         if (n < *fdl)
 862                 debug("XXX shrink: %d < %d", n, *fdl);
 863         *fdl = n;
 864         memset(*fdrp, 0, sz);
 865         memset(*fdwp, 0, sz);
 866
 867         for (i = 0; i < sockets_alloc; i++) {
 868                 switch (sockets[i].type) {
 869                 case AUTH_SOCKET:
 870                 case AUTH_CONNECTION:
 871                         FD_SET(sockets[i].fd, *fdrp);
 872                         if (buffer_len(&sockets[i].output) > 0)
 873                                 FD_SET(sockets[i].fd, *fdwp);
 874                         break;
 875                 default:
 876                         break;
 877                 }
 878         }
 879         return (1);
 880 }
 881
 882 static void
 883 after_select(fd_set *readset, fd_set *writeset)
 884 {
 885         struct sockaddr_un sunaddr;
 886         socklen_t slen;
 887         char buf[1024];
 888         int len, sock;
 889         u_int i;
 890         uid_t euid;
 891         gid_t egid;
 892
 893         for (i = 0; i < sockets_alloc; i++)
 894                 switch (sockets[i].type) {
 895                 case AUTH_UNUSED:
 896                         break;
 897                 case AUTH_SOCKET:
 898                         if (FD_ISSET(sockets[i].fd, readset)) {
 899                                 slen = sizeof(sunaddr);
 900                                 sock = accept(sockets[i].fd,
 901                                     (struct sockaddr *)&sunaddr, &slen);
 902                                 if (sock < 0) {
 903                                         error("accept from AUTH_SOCKET: %s",
 904                                             strerror(errno));
 905                                         break;
 906                                 }
 907                                 if (getpeereid(sock, &euid, &egid) < 0) {
 908                                         error("getpeereid %d failed: %s",
 909                                             sock, strerror(errno));
 910                                         close(sock);
 911                                         break;
 912                                 }
 913                                 if ((euid != 0) && (getuid() != euid)) {
 914                                         error("uid mismatch: "
 915                                             "peer euid %u != uid %u",
 916                                             (u_int) euid, (u_int) getuid());
 917                                         close(sock);
 918                                         break;
 919                                 }
 920                                 new_socket(AUTH_CONNECTION, sock);
 921                         }
 922                         break;
 923                 case AUTH_CONNECTION:
 924                         if (buffer_len(&sockets[i].output) > 0 &&
 925                             FD_ISSET(sockets[i].fd, writeset)) {
 926                                 do {
 927                                         len = write(sockets[i].fd,
 928                                             buffer_ptr(&sockets[i].output),
 929                                             buffer_len(&sockets[i].output));
 930                                         if (len == -1 && (errno == EAGAIN ||
 931                                             errno == EINTR))
 932                                                 continue;
 933                                         break;
 934                                 } while (1);
 935                                 if (len <= 0) {
 936                                         close_socket(&sockets[i]);
 937                                         break;
 938                                 }
 939                                 buffer_consume(&sockets[i].output, len);
 940                         }
 941                         if (FD_ISSET(sockets[i].fd, readset)) {
 942                                 do {
 943                                         len = read(sockets[i].fd, buf, sizeof(buf));
 944                                         if (len == -1 && (errno == EAGAIN ||
 945                                             errno == EINTR))
 946                                                 continue;
 947                                         break;
 948                                 } while (1);
 949                                 if (len <= 0) {
 950                                         close_socket(&sockets[i]);
 951                                         break;
 952                                 }
 953                                 buffer_append(&sockets[i].input, buf, len);
 954                                 process_message(&sockets[i]);
 955                         }
 956                         break;
 957                 default:
 958                         fatal("Unknown type %d", sockets[i].type);
 959                 }
 960 }
 961
 962 static void
 963 cleanup_socket(void)
 964 {
 965         if (socket_name[0])
 966                 unlink(socket_name);
 967         if (socket_dir[0])
 968                 rmdir(socket_dir);
 969 }
 970
 971 void
 972 cleanup_exit(int i)
 973 {
 974         cleanup_socket();
 975         _exit(i);
 976 }
 977
 978 /*ARGSUSED*/
 979 static void
 980 cleanup_handler(int sig)
 981 {
 982         cleanup_socket();
 983         _exit(2);
 984 }
 985
 986 /*ARGSUSED*/
 987 static void
 988 check_parent_exists(int sig)
 989 {
 990         int save_errno = errno;
 991
 992         if (parent_pid != -1 && kill(parent_pid, 0) < 0) {
 993                 /* printf("Parent has died - Authentication agent exiting.\n"); */
 994                 cleanup_handler(sig); /* safe */
 995         }
 996         mysignal(SIGALRM, check_parent_exists);
 997         alarm(10);
 998         errno = save_errno;
 999 }
1000
1001 static void
1002 usage(void)
1003 {
1004         fprintf(stderr, "Usage: %s [options] [command [args ...]]\n",
1005             __progname);
1006         fprintf(stderr, "Options:\n");
1007         fprintf(stderr, "  -c          Generate C-shell commands on stdout.\n");
1008         fprintf(stderr, "  -s          Generate Bourne shell commands on stdout.\n");
1009         fprintf(stderr, "  -k          Kill the current agent.\n");
1010         fprintf(stderr, "  -d          Debug mode.\n");
1011         fprintf(stderr, "  -a socket   Bind agent socket to given name.\n");
1012         fprintf(stderr, "  -t life     Default identity lifetime (seconds).\n");
1013         exit(1);
1014 }
1015
1016 int
1017 main(int ac, char **av)
1018 {
1019         int c_flag = 0, d_flag = 0, k_flag = 0, s_flag = 0;
1020         int sock, fd, ch;
1021         u_int nalloc;
1022         char *shell, *format, *pidstr, *agentsocket = NULL;
1023         fd_set *readsetp = NULL, *writesetp = NULL;
1024         struct sockaddr_un sunaddr;
1025 #ifdef HAVE_SETRLIMIT
1026         struct rlimit rlim;
1027 #endif
1028         int prev_mask;
1029         extern int optind;
1030         extern char *optarg;
1031         pid_t pid;
1032         char pidstrbuf[1 + 3 * sizeof pid];
1033
1034         /* Ensure that fds 0, 1 and 2 are open or directed to /dev/null */
1035         sanitise_stdfd();
1036
1037         /* drop */
1038         setegid(getgid());
1039         setgid(getgid());
1040         setuid(geteuid());
1041
1042 #if defined(HAVE_PRCTL) && defined(PR_SET_DUMPABLE)
1043         /* Disable ptrace on Linux without sgid bit */
1044         prctl(PR_SET_DUMPABLE, 0);
1045 #endif
1046
1047         SSLeay_add_all_algorithms();
1048
1049         __progname = ssh_get_progname(av[0]);
1050         init_rng();
1051         seed_rng();
1052
1053         while ((ch = getopt(ac, av, "cdksa:t:")) != -1) {
1054                 switch (ch) {
1055                 case 'c':
1056                         if (s_flag)
1057                                 usage();
1058                         c_flag++;
1059                         break;
1060                 case 'k':
1061                         k_flag++;
1062                         break;
1063                 case 's':
1064                         if (c_flag)
1065                                 usage();
1066                         s_flag++;
1067                         break;
1068                 case 'd':
1069                         if (d_flag)
1070                                 usage();
1071                         d_flag++;
1072                         break;
1073                 case 'a':
1074                         agentsocket = optarg;
1075                         break;
1076                 case 't':
1077                         if ((lifetime = convtime(optarg)) == -1) {
1078                                 fprintf(stderr, "Invalid lifetime\n");
1079                                 usage();
1080                         }
1081                         break;
1082                 default:
1083                         usage();
1084                 }
1085         }
1086         ac -= optind;
1087         av += optind;
1088
1089         if (ac > 0 && (c_flag || k_flag || s_flag || d_flag))
1090                 usage();
1091
1092         if (ac == 0 && !c_flag && !s_flag) {
1093                 shell = getenv("SHELL");
1094                 if (shell != NULL &&
1095                     strncmp(shell + strlen(shell) - 3, "csh", 3) == 0)
1096                         c_flag = 1;
1097         }
1098         if (k_flag) {
1099                 const char *errstr = NULL;
1100
1101                 pidstr = getenv(SSH_AGENTPID_ENV_NAME);
1102                 if (pidstr == NULL) {
1103                         fprintf(stderr, "%s not set, cannot kill agent\n",
1104                             SSH_AGENTPID_ENV_NAME);
1105                         exit(1);
1106                 }
1107                 pid = (int)strtonum(pidstr, 2, INT_MAX, &errstr);
1108                 if (errstr) {
1109                         fprintf(stderr,
1110                             "%s=\"%s\", which is not a good PID: %s\n",
1111                             SSH_AGENTPID_ENV_NAME, pidstr, errstr);
1112                         exit(1);
1113                 }
1114                 if (kill(pid, SIGTERM) == -1) {
1115                         perror("kill");
1116                         exit(1);
1117                 }
1118                 format = c_flag ? "unsetenv %s;\n" : "unset %s;\n";
1119                 printf(format, SSH_AUTHSOCKET_ENV_NAME);
1120                 printf(format, SSH_AGENTPID_ENV_NAME);
1121                 printf("echo Agent pid %ld killed;\n", (long)pid);
1122                 exit(0);
1123         }
1124         parent_pid = getpid();
1125
1126         if (agentsocket == NULL) {
1127                 /* Create private directory for agent socket */
1128                 strlcpy(socket_dir, "/tmp/ssh-XXXXXXXXXX", sizeof socket_dir);
1129                 if (mkdtemp(socket_dir) == NULL) {
1130                         perror("mkdtemp: private socket dir");
1131                         exit(1);
1132                 }
1133                 snprintf(socket_name, sizeof socket_name, "%s/agent.%ld", socket_dir,
1134                     (long)parent_pid);
1135         } else {
1136                 /* Try to use specified agent socket */
1137                 socket_dir[0] = '\0';
1138                 strlcpy(socket_name, agentsocket, sizeof socket_name);
1139         }
1140
1141         /*
1142          * Create socket early so it will exist before command gets run from
1143          * the parent.
1144          */
1145         sock = socket(AF_UNIX, SOCK_STREAM, 0);
1146         if (sock < 0) {
1147                 perror("socket");
1148                 *socket_name = '\0'; /* Don't unlink any existing file */
1149                 cleanup_exit(1);
1150         }
1151         memset(&sunaddr, 0, sizeof(sunaddr));
1152         sunaddr.sun_family = AF_UNIX;
1153         strlcpy(sunaddr.sun_path, socket_name, sizeof(sunaddr.sun_path));
1154         prev_mask = umask(0177);
1155         if (bind(sock, (struct sockaddr *) &sunaddr, sizeof(sunaddr)) < 0) {
1156                 perror("bind");
1157                 *socket_name = '\0'; /* Don't unlink any existing file */
1158                 umask(prev_mask);
1159                 cleanup_exit(1);
1160         }
1161         umask(prev_mask);
1162         if (listen(sock, SSH_LISTEN_BACKLOG) < 0) {
1163                 perror("listen");
1164                 cleanup_exit(1);
1165         }
1166
1167         /*
1168          * Fork, and have the parent execute the command, if any, or present
1169          * the socket data.  The child continues as the authentication agent.
1170          */
1171         if (d_flag) {
1172                 log_init(__progname, SYSLOG_LEVEL_DEBUG1, SYSLOG_FACILITY_AUTH, 1);
1173                 format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1174                 printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1175                     SSH_AUTHSOCKET_ENV_NAME);
1176                 printf("echo Agent pid %ld;\n", (long)parent_pid);
1177                 goto skip;
1178         }
1179         pid = fork();
1180         if (pid == -1) {
1181                 perror("fork");
1182                 cleanup_exit(1);
1183         }
1184         if (pid != 0) {         /* Parent - execute the given command. */
1185                 close(sock);
1186                 snprintf(pidstrbuf, sizeof pidstrbuf, "%ld", (long)pid);
1187                 if (ac == 0) {
1188                         format = c_flag ? "setenv %s %s;\n" : "%s=%s; export %s;\n";
1189                         printf(format, SSH_AUTHSOCKET_ENV_NAME, socket_name,
1190                             SSH_AUTHSOCKET_ENV_NAME);
1191                         printf(format, SSH_AGENTPID_ENV_NAME, pidstrbuf,
1192                             SSH_AGENTPID_ENV_NAME);
1193                         printf("echo Agent pid %ld;\n", (long)pid);
1194                         exit(0);
1195                 }
1196                 if (setenv(SSH_AUTHSOCKET_ENV_NAME, socket_name, 1) == -1 ||
1197                     setenv(SSH_AGENTPID_ENV_NAME, pidstrbuf, 1) == -1) {
1198                         perror("setenv");
1199                         exit(1);
1200                 }
1201                 execvp(av[0], av);
1202                 perror(av[0]);
1203                 exit(1);
1204         }
1205         /* child */
1206         log_init(__progname, SYSLOG_LEVEL_INFO, SYSLOG_FACILITY_AUTH, 0);
1207
1208         if (setsid() == -1) {
1209                 error("setsid: %s", strerror(errno));
1210                 cleanup_exit(1);
1211         }
1212
1213         (void)chdir("/");
1214         if ((fd = open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
1215                 /* XXX might close listen socket */
1216                 (void)dup2(fd, STDIN_FILENO);
1217                 (void)dup2(fd, STDOUT_FILENO);
1218                 (void)dup2(fd, STDERR_FILENO);
1219                 if (fd > 2)
1220                         close(fd);
1221         }
1222
1223 #ifdef HAVE_SETRLIMIT
1224         /* deny core dumps, since memory contains unencrypted private keys */
1225         rlim.rlim_cur = rlim.rlim_max = 0;
1226         if (setrlimit(RLIMIT_CORE, &rlim) < 0) {
1227                 error("setrlimit RLIMIT_CORE: %s", strerror(errno));
1228                 cleanup_exit(1);
1229         }
1230 #endif
1231
1232 skip:
1233         new_socket(AUTH_SOCKET, sock);
1234         if (ac > 0) {
1235                 mysignal(SIGALRM, check_parent_exists);
1236                 alarm(10);
1237         }
1238         idtab_init();
1239         if (!d_flag)
1240                 signal(SIGINT, SIG_IGN);
1241         signal(SIGPIPE, SIG_IGN);
1242         signal(SIGHUP, cleanup_handler);
1243         signal(SIGTERM, cleanup_handler);
1244         nalloc = 0;
1245
1246         while (1) {
1247                 prepare_select(&readsetp, &writesetp, &max_fd, &nalloc);
1248                 if (select(max_fd + 1, readsetp, writesetp, NULL, NULL) < 0) {
1249                         if (errno == EINTR)
1250                                 continue;
1251                         fatal("select: %s", strerror(errno));
1252                 }
1253                 after_select(readsetp, writesetp);
1254         }
1255         /* NOTREACHED */
1256 }